A constrained-geometry catalyst (CGC) [Me2Si(η5-Me4C5)NtBu]TiCl2 is one of the most typical and most representative, commercialized catalysts among homogeneous Ziegler-Natta olefinic polymerization catalyst (metallocene catalyst) systems. A cocatalyst-activated CGC has the following advantages over the conventional metallocene catalysts: (1) it shows a high level of activity even at a higher polymerization temperature, allowing the production of high molecular weight polymers, and (2) it also provides an excellent degree of copolymerization for sterically hindered α-olefinic monomers such as 1-hexene and 1-octene. Besides, as various characteristics thereof became known in the art, vigorous efforts was made in the academic and industrial circles to synthesize and use CGC catalyst derivatives as a polymerization catalyst for different purposes (Chem. Rev., 2003, 103, 283).
Meanwhile, a Group IV transition metal compound (Tr, Zr) including a phenoxy imine moiety as its basic skeleton was developed by Mitzui Co. Ltd. (Japan), showing an excellent activity and capability such as various control, living polymerizations of polypropylene as well as polyethylene. The catalyst is characterized in that its structure is free from a cyclopentadienyl ligand, the major skeleton of the conventional metallocene catalyst or the CGC. For that reason, this catalyst came into the spotlight as a post metallocene catalyst, i.e., a next generation catalyst departing from the metallocene structure. Thereafter, it was denominated as “FI catalyst,” and its activity and effectiveness depending on various substituents surrounding the basic skeleton of the catalyst was carefully scrutinized. Up to date, it has been cited in numerous references. (J. Am. Chem. Soc. 2001, 123, 6847 and 2002, 124, 3327).

Recently, LG Chem. Ltd. developed some catalysts with a ligand wherein a phenyl group was introduced into a CGC backbone as another bridge (Organometallics, 2006, 25, 5122 and 2008, 27, 3907). In current levels of preparing an ethylene/1-octene copolymer, this catalyst exhibited an activity, a molecular weight, and the content of 1-octene that are equal to or higher than that of the conventional CGC.
